The Diablo III Auction House Has Been Shut Down
The Diablo III in-game auction house is gone according to Kotaku. This was the most hates feature of the game and is now removed as promised. The developer Blizzard did announce this move already some time ago.
Transactions can only be claimed until June 24 2014 but searching and bidding is not possible anymore. You need to find or craft your gear from now on.